Multiconnector having an insulating base and plural resilient contact strips



July 9, 1968 MORIMITSU NAKAZAWA 3,3 66

MULTICONNECTOR HAVING AN INSULATING BASE AND PLURAL RESILIENT CONTACT STRIPS Filed March 17, 1967 3 Sheets-Sheet 1 1 N VEN TOR. 4/0/7/"1/6'0 A aaza are July 9, 1 MORIMITSU NAKAZAWA 3,392, 66

MULTICONNECTOR HAVTNG AN INSULATING BASE AND PLURAL RESILIENT CONTACT STRIPS Filed March N, 1967 5 Sheets-Sheet .2

p 151-5.! m (m 111 ug I21 I21 L [Ha] I Ha, (m

H4 1 n5 7 H5 H6- we 3I5-fi 316-0 316 INVENTOR.

m ATTORNEYS J ly 9,1968 MORIMITSU NAKAZAWA 3, 66

MULTICONNECTOR HAVING AN INSULATING BASE AND PLURAL RESILIENT CONTACT STRIPS Filed March .17, 1967 3 Sheets-Sheet 5 a 1 I 2 A A A A A 0,3 A 'F. 4

ig-1E R C A -A"\r 9 0 51002025000540 INVENTOR.

Mamba/Via flakazatlfa BY ATTORNEYS United States Patent 3,392,366 MULTICONNECTOR HAVING AN INSULAT- ING BASE AND PLURAL RESILIENT CON- TACT STRIPS Morimitsu Nakazawa, Chofu-shi, Japan, assignor to Taiyo Yuden Kabushikikaisha, Tokyo, Japan, a corporation of Japan Filed Mar. 17, 1967, Ser. No. 624,089 Claims priority, application Japan, Oct. 26, 1966, il/70,576 Claims. (Cl. 339-476) ABSTRACT OF THE DISCLOSURE An apparatus for receiving a printed-circuit board having an insulating base and a female terminal. The female terminal consists of a plurality of resilient contact strips which are assembled with one another and inserted to each room formed in the insulating base so as to contact with the printed-circuit end at least three points.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to an electric circuit connector or the so-called multiconnector, and more particularly to a new and novel multijack or multiconnector having a specific female terminal consisting of a plurality of resilient contact strips for positively and smoothly contacting with the circuit ends of a printed-circuit board with a possibly small contact pressure.

Description of the prior art In general, a multijack or multiconnector having female terminal contacts with printed-circuit ends of the printed circuit board with rather great contact pressure. Accordingly, the metal plated on the printed-circuit ends is liable to wear away. Furthermore, due to constructional feature of resilient contact strips forming the female terminals, positive contact of the printed-circuit end with the female terminals cannot be appreciated.

SUMMARY OF THE INVENTION One object of this invention is to provide a multiconnector which electrically contacts the circuit ends of a printed-circuit board under as small a contact pressure as possible.

Another object of this invention is to provide a multiconnector having female terminals, each contacting each circuit end of a printed-circuit board at several points so as to minimize electric contact resistance therebetween.

Briefly, the multijack or multiconnector of the present invention utilizes a specific female terminal consisting of at least two resilient contact strips having specific construction so that the multiconnector of the present invention positively contact with the circuit end of the printed circuit board with small contact pressure so that almost no metal plated on the circuit end is worn away.

Other objects, features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF DRAWINGS FIGURE 1 is an enlarged fragmentary perspective view illustrating an insulating base of a multiconnector according to the present invention;

FIGURE 2 is a cross-sectional view of the insulating base, shown in FIGURE 1, with which female terminals of the present invention are assembled;

FIGURE 3 is a side view illustrating one example of a first resilient contact strip of the female terminal shown in FIGURE 2;

FIGURE 4 is a front view of the first resilient contact strip shown in FIGURE 3;

FIGURE 5 is a side view illustrating one example of a second resilient strip of the female terminal shown in FIGURE 2;

FIGURE 6 is its front view;

FIGURE 7 is a side view illustrating another example of the female terminal according to the present invention;

FIGURE 8 is a front view illustrating a first resilient contact strip of the female terminal shown in FIGURE 7;

FIGURE 9 is a perspective view of a second resilient contact strip of the female terminal shown in FIGURE 7;

FIGURE 10 is a side view illustrating another example of the female terminal according to the present invention;

FIGURE 11 is a side view illustrating still another example of the female terminal used in the present invention;

FIGURE 12 is a front view illustrating a first resilient contact strip of the female terminal shown in FIGURE 11;

FIGURE 13 is a front view illustrating a second resilient contact strip of the female terminal;

FIGURE 14 is a graph showing the characteristics of the multiconnector of this invention, obtained in experiments, in comparison with those of a prior art multiconnector;

FIGURE 15 is a graph showing the wear-proof characteristics of the multiconnector of this invention obtained in experiments; and

FIGURES 16A and 16B showing other characteristics of the multiconnector of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the drawings one example of this invention will hereinafter be described in detail. In FIG- URES 1 and 2 reference numeral 1 designates an insulating base made of an insulating material such, for example, as plastics or the like. Reference numeral 2 indicates a groove formed in the insulating base 1 along its center line for receiving a printed-circuit board 3. On the opposite side walls of the groove 2 there are respectively provided at predetermined intervals a plurality of partition walls 4 made of an insulating material such as. for example, plastics or the like, each partition wall 4 on one side wall confronting each partition wall 4 on the other side wall. As a result of this, a plurality of rooms 5 are formed along the side walls, the rooms 5 on one side wall being precisely opposite those on the other side wall. While the partition walls 4 project centrally of the groove 2 from the side walls thereof, the confronting end faces of the opposed partition walls are spaced at predetermined distance, namely defining a gap therebetween. The width of the gap is selected to be slightly greater than the thickness t of the printed-circuit board 3 so as to facilitate inserting of the printed-circuit board 3 into the groove 2. In this invention the aforesaid insulating base 1 and partition walls 4 can be formed integrally of the same material by means of, for example, molding.

A resilient female terminal 6, made of conductive metallic material such as, for example, beryllium-copper alloy or the like, is attached to each room 5 formed in the insulating base, completing a multiconnector of this invention. Accordingly, when the printed-circuit board is inserted into the gap of the multiconnector, each female terminal 6 attached to each room 5 makes electrical contact with each circuit end 7 of the printed-circuit board 3 at several points.

A description will be given in connection with some different female terminals employed in the multiconnector of this invention which are disposed on, for example, the right side walls of the groove in the drawing.

Referring now to FIGURES 3 to 6, the female terminal 6 will be described in detail. In FIGURES 3 and 4 reference numeral 8 indicates generally a first resilient contact strip made of a metal such as the aforementioned beryllium-copper alloy or the like. The first resilient contact strip 8 consists of a forked contact portion 9 making direct contact with the circuit end 7 of the printed-circuit board 3 and a base portion 10 equipped with means for attaching the female terminal 6 to the insulating base 1 and means for external connection. That is, the contact part 9 comprises a contact portion 11 projecting centrally of the groove 2 and making contact with the circuit end 7 of the printed-circuit board 3 when attached to the insulating base 1 and an engaging end portion 13 projecting in the direction opposite from the projecting contact portion 11 and bent downward for engagement with a top 12a of the inner wall of an engaging recess 12 formed in the insulating base 1. The base portion 10 is generally substantially fiat and has set up therefrom substantially at right angles thereto a lug 14 projecting centrally of the groove 2 in the vicinity of the portion contiguous to the contact part 9 and a tongue 15 set up under the lug 14 at a position spaced a predetermined distance therefrom. Further, the base portion 10 has bored therein an aperture 16 near the free end for external connection, as illustrated in FIGURE 4.

FIGURE 4 is a front view of the first resilient contact strip 8 depicted in FIGURE 3. As is apparent from the figure, the contact part 9 has formed therein a slit 17 in the lengthwise direction thereof and hence is forkshaped. The width W of the slit 17 is selected to decrease gradually from the vicinity of the bent portion C of the resilient contact strip 8 to its end so as to provide for enhanced mechanical strength of that portion. Due to the provision of the slit 17, the resilient contact strip 8 makes contact with the circuit end 7 of the printed-circuit board at two points 11 and 11.

FIGURE 5 is a side view of a second resilient contact strip 18 which is employed in combination with the first resilient contact strip 8 and is made of the same material as the first contact strip 8. The second resilient contact strip 18 consists of a portion 19 making direct contact with the circuit end 7 of the printed-circuit board 3 and a flat portion 20 contiguous to the portion 19. The portion 19 is curved toward the center of the groove 2 as identified at 21, extending upwardly of the fiat portion 20 and making contact with the circuit end 7 of the printed-circuit board 3 when attached to the insulating base 1. As is apparent from FIGURE 6 illustrating a front view of the second resilient contact strip 18, the free end portion of the portion 19 is in the form of a T. Namely, the free end of the portion 19 has formed thereon projections 22 and 23 projecting in the lateral direction. The width W of the free end of the portion 19, the width W of the portion 19 and the width W of the groove 2 are selected in such a relationship that W W W The projections 22 and 23 are provided to ensure that the portion 19 would not excessively project toward the center of the groove 2 through the slit 17. As is clearly seen from FIGURES 2, 3 and 5, the curvature of the contact portion 19 of the second resilient contact strip 18 is greater than that of the projecting contact portion 11 of the first resilient contact strip 8. Therefore, the contact portion of the second resilient contact strip 18 is subjected to a stress, by the end edge of the printed circuit end, greater than that applied to the projecting contact portion 11 of the first resilient contact strip 8 when the printed-circuit board 3 is inserted into the groove 2. Especially, the contact portion of the second resilient contact strip is applied a considerably great downward force by the square end of the printed-circuit board 3 shown in FIG- URE 2, with the result that the contact portion 19 of the second resilient contact strip 18 is likely to be curved excessively toward the center of the groove 2 and broken. By the provision of the projections 22 and 23, however, such breakage of the contact portion 19 is prevented. That is, the width W of the free end of the portion 19 is greater than the width W of the slit 17, so that when the projecting contact portion 21 of the second resilient contact strip 18 is pressed by the end of the printed-circuit board 3 to be excessively bent toward the center of the groove 2 the projections 22 and 23 come to engage with the slit 17, thus effectively preventing the projecting contact portion 21 from being excessively curved.

The female terminal 6 of the present invention is constituted by the first and second resilient contact strips 8 and 18 assembled with each other. In FIGURE 2 there are ilustrated the female terminals 6 attached to the insulating base 1. Further, the widths of the fiat portions 10 and 20 of the first and second resilient contact strips 8 and 18 are selected to be the same. Accordingly, when the two resilient strips 8 and 18 are assembled with each other, the respective flat portions 10 and 20 join together and the contact portion 21 of the second resilient contact strip 18 may project toward the center of the groove 2 through the slit 17 of the first resilient contact strip 8. The first and second resilient contact strips 8 and 18 are each made of a strip of resilient material and this facilitates attaching of the contact strips to the insulating base 1.

The female terminal '6 thus assembled is attached to the insulating base 1 in such a manner as will hereinbelow be described. That is, the female terminal 6 is inserted into the groove 2 along the side wall 24 of the groove 2 until the lug 14 of the first resilient contact strip 8 arrives at the upper surface 27 of the bottom 25 of the base 1 while the flat portion of the female terminal 6 being inserted into a gap 26 defined by the side wall 24 and the bottom 25 of the base 1. Then, the tongue 15 of the first resilient contact strip 8 is set up therefrom and at this position the free end of the tongue 15 engages with the underside surface 28 of the bottom 25 from underneath. In this manner, the female terminal 6 is firmly attached to the insulating base 1, which is illustrated in FIGURE 2.

The multiconnector having the aforesaid female terminal 6 installed in each room 5 of the insulating base 1 is used for receiving the printed-circuit board 3. The thickness and the width of the projecting contact portions of the first and second resilient contact strips are appreciably small, so that each resilient contact strip exhibits a high degree of flexibility. Further, as is apparent from FIGURES 3 to 5, the fulcra of the spring action of the contact portions 11, 11 and 21 are all different and hence these contact portions can each exhibit spring stress independently of the others. Since the contact portions 11 and 11 are so designed as to be considerably fiexible, these two contact portions can make contact with the circuit end of the printed-circuit board 3 in response to distortion of the circuit ends or irregularity of their thickness. While, the contact portion 21 engages the circuit end of the printed-circuit board 3 by a spring action which is quite different from those of the above-mentioned contact portions 11 and 11'. Consequently, the female terminal 6 of this invention contacts the circuit end of the printed-circuit board 3 at three points.

With such an arrangement as has been described in the foregoing, the contact resistance of each contact portion resulting from contact with the printed-circuit board can be reduced to approximately one-third of that obtained with a female terminal of a single contact structure, in which the distance from the contact point to such a hole as identified at 16 in FIGURE 4 is the same as that in the female terminal of this invention. Further, with this invention, probability of contact of the female terminal with the printed-circuit board 3 can be raised up to approximately triple product of that obtainable with the female terminal of the single contact structure. Namely, the contact structure of this invention is highly reliable. My experiments show that the contact resistance of the beryllium plated female terminal of this invention caused by contact with .one side of a printed-circuit board having circuit ends plated with, for instance, rhodium, is approximately 2.0 to 2.5 milliohms and that the degree of variance of the measured resistance value is extremely low. According to my experiments, the contact resistance of the prior art female terminal resulting from contact with one side of the printed-circuit board is approximately 4 to 8 milliohms and the degree of variance of the resistance value is considerably high.

Further, in this invention, when the printed-circuit board 3 depicted in FIGURE 2 is inserted into a gap g between the contact portions of the opposing female terminals 6, the both sides of the printed-circuit board 3 are subjected to stress by the contact portions 11, 11' and 21 of the female terminals 6, since the width W of the gap g is selected smaller than the thickness t of the printed-circuit board 3. The stress mentioned just above is a unit of the force for inserting the printed-circuit board 3 into the groove 2 and for pulling out the board 3 from the groove 2. Supposing that the force of the conventional right or left single female terminal exerted on one side of the printed-circuit board is 300g, the mathematical mean value of the force of contact portions 11, 11' and 21 of the female terminals of this invention exerted on the printed-circuit board held therebetween is 100g at each contact portion. That is, this leads to a considerable reduction of abrasion and fatigue .of the contact portions 11, 11' and 21 as compared with that of the prior art female terminal. Consequently, the female terminal of this invention is excellent in shock resistance and is suitable for use in the case where the printed-circuit board is often inserted into and removed from a connector. Further, even if the printed-circuit board is left long inserted into the connector, probability of contact by the respective contact portions of the female terminal of this invention is high. Thus, this invention provides a multi-connector which is extremely stable in operation.

In FIGURES 7 to 9 there is illustrated another modified form of the female terminal for use in this invention. FIGURE 7 is a side view of a female terminal which consists of first and second resilient contact strips 108 and 118. FIGURES 8 and 9 are front and perspective views of the first and second resilient contact strips 108 and 118. The first and second resilient contact strips 108 and 118 are assembled with each other and attached to the insulating base 1 in substantially the same manner as in the case of the aforesaid female terminal 6, and hence no detailed description will be given in this specification.

In the example depicted in FIGURE 7 the first resilient contact strip 108 has two pairs of contact points 111, 111' and 111a, 111a. That is, the contact portion of the first resilient contact strip 108 forming the contacts is corrugated having at least two projections ,or dents. While, the second resilient contact strip 118 has a contact point 121 projecting between the two pairs of contact points of the first resilient contact strip 108. That is, the second resilient contact strip 118 extends along the side wall 24 of the insulating base 1 up to its top and is bent downward in the direction of the center of the groove 2, providing the contact 121 between the aforementioned two pairs of contacts, as illustrated in FIGURE 9. The female terminal 106 depicted in FIGURE 7 contacts the circuit end of the printed-circuit board at five points. In this female terminal 106 all the contact points are adjusted to project so as to make contact with the same plane P perpendicular with respect to the paper, as shown in FIGURE 7. In addition, the plane P crosses an extension (the flat portion itself in this example) of the fiat portion of the female terminal 106 at an acute angle a.

When the printed-circuit board is inserted into the groove 2 of the insulating base of the multiconnector equipped with the female terminals 106, the upper and lower projecting contact portions 111, 111 and 111a,

111a are displaced with the bent portion 114 as a fulcrum. In this case, however, the displacement degree of the upper projecting contact portions 111 and 111 is greater than that of the lower projecting contact portions 111a and 111a and the spring force of the upper projecting contact portions 111 and 111 is Weaker than that of the lower ones 111a and 11111, so that the upper contact portions readily conform to the plane of the printed-circuit board and then the lower contact portions slightly conform to the plane of the printed-circuit board. In other words, the upper projecting contact portions are greatly bent to contact the printed-circuit board and the lower ones are slightly bent to contact the circuit end of the printed-circuit board. In order that the upper and lower projecting contact portions may closely contact the printed-circuit board, it is required that the contact portions 111', 111a and 111, 111a constituting the fork-shaped portion of the resilient contact strip 108 are fully small in thickness and in width so as to be flexible. Due to the flexibility, the free end of the first resilient contact strip 108 is easily shifted from the inner left wall to the right wall of the engaging recess 12 when the printed-circuit board is inserted, and hence the insertion of the printed-circuit board is completed without pressing the free end of the first resilient contact strip against the right wall of the recess 12. Namely, it can be regarded that the contact portions 111, 111 and 111a, 111a are scarcely subjected to spring stress with the right wall as a fulcrum. Accordingly, the force of the first resilient contact strip 108 acting on the printed-circuit board is produced only by a stress caused with the bent portion 4 as a fulcrum, and hence insertion of the printed-circuit board becomes smooth. Further, in the example it can be said that the second resilient contact strip 118 does not ever cooperate with the first resilient contact strip and has a spring fulcrum different from that of the first resilient, contact strip 108 and is bent down in the direction of the groove 2 of the insulating base 1 as illustrated in the figure. Consequently, the second resilient contact strip also facilitates insertion of the printed-circuit board. That is, the projecting contact portion 121 of the second resilient contact strip 118 constitutes a fifth contact strip of the female terminal 106. Thus, an elongated strip of resilient material constitutes a female terminal having five contact points. In this case, the printed-circuit board is inserted into the groove until the angle on between the aforementioned plane P and the resilient contact strip becomes substantially zero, and the free end of the first resilient contact strip reaches the right wall of the engaging recess 12.

FIGURE 10 is a side view of a female terminal 206 substantially similar to that depicted in FIGURE 7. As is apparent from a comparison of these two figures, the female terminal depicted in FIGURE 10 differs from that shown in FIGURE 7 in that a plane Q which is perpendicular with respect to the paper and with which projecting contact portions 211, 211, 221, 211a and 21111 of first and second resilient contact strips 208 and 218 contact crosses an extension of the flat portion of the female terminal 206 at an acute angle 6 above the female terminal. In other words, the degree of each projection of the projecting contact portions toward the center of the groove 2 becomes increased as the bottom of the groove 2 is approached. That is, the projection state of the projecting contact portions is opposite to that in the example shown in FIGURE 7. Another difference lies in that the free end 201 of the first resilient contact strip 208 engages with the right side Wall of the engaging recess 12 of the insulating base 1, as shown in FIGURE 10. When the printed-circuit board is inserted into the groove of the insulating base equipped with the above female terminal 206, the upper projecting portions 211 and 211' of the first resilient contact strip 208 first come into contact with the printed-circuit board and are displaced to right (in FIGURE 10). In this case, however, since the free end 201 of the first resilient contact strip is in engagement with the right side wall of the engaging recess 12 of the insulating base 1, the engaging point functions as a fulcrum of the first resilient contact strip 208. Accordingly, the rightward displacement of the upper projecting portions 211 and 211' of the first resilient contact strip 208 does not exert so great influence upon the lower projecting contact portions 211a and 211a. When the printed-circuit board is further inserted into the groove 2, the printed-circuit board makes contact with the projecting contact portion 221 of the second resilient contact strip 218 and then readily engages with the lower projecting contact portions 211a and 211a of the first resilient contact strip 208. In this case, since the displacement degree of the projecting contact portions 211a and 211a to right is greater than that of the upper projecting contact portions and the free end 201 of the upper projecting portions 211 and 211 functions as a fulcrum, the displacement of the lower projecting contact portions 211a and 211a" to right hardly affects the upper projecting contact portions 211 and 211' of the first resilient contact strip 208. Accordingly, both the projecting contact portions can act substantially independently, so that the spring force of the trough portion of the first contact strip may be made small. Thus, contact is ensured of the printed-circuit board with the upper and lower projecting contact portions. In the present example, the insertion of the printed-circuit board is very easy, because the lower projecting contact portion 211a and 211a are further to the center of the groove 2 than the upper projecting contact portions 211, 211 and 221.

FIGURES 11 to 13 illustrate still another modification of the female terminal employed in this invention. In this example a first resilient contact strip 308 is substantially the same as those 108 and 208 of the female terminals 106 and 206 shown in FIGURES 7 and 10 in its construction but, as is apparent from FIGURES 11 to 13, a second resilient contact strip 318 is different from those 118 and 218 of the female terminals 106 and 206 but is exactly the same in configuration as that 18 of the female terminal 6 depicted in FIGURES 3 to 6 and is substantially the same in purpose and function. The female terminal identified at 306 in this example is different from the female terminal 6 in that the former has five contact points and is different from the female terminals 106 and 206 in that the projecting contact portions equally project toward the center of the groove. As will be understood from the foregoing, the female terminal 306 possesses the operational effect attained by combination of those of the aforementioned female terminals 6, 106 and 206.

In FIGURE 14 there are illustrated the characteristics of the multiconnector of this invention, obtained in experiments, in comparison with those of a prior art multiconnector. The female terminals of the multi-connectors of this invention and the prior art employed in the experiments were those made of a Be-Cu alloy and plated with gold, and the circuit ends of the printed-circuit boards inserted into such multiconnectors were plated with rhodium thereon. In the figure the ordinate represents the resistance value R in milliohm (m0) between the aperture to which a lead wire is connected and the point making contact with the circuit end of the printed-circuit board and the abscissa the number N of the female terminals of the multiconnector, the curves a and :1 indicating the characteristics of the prior art multiconnectors and the curves a and a indicating those of the multiconnectors of this invention. As is apparent from the figure, the resistance values of the multiconnectors of this invention are appreciably lower than those of the prior art multiconnector, and in addition the resistance value of each female terminal of this invention is substantially equal to those of the others.

FIGURE 15 illustrates results of my experiments conducted on the wearproof characteristics of the multiconnector of this invention. In this case the female terminal and circuit ends as used in the case of FIGURE 14 are used. The ordinate and the abscissa represent the same as those in FIGURE 14. Reference numeral b indicates the resulted curve obtained after the circuit ends of the printed-circuit board had been inserted into and pulled out of the multiconnector 1000 times and b the resulted curve similarly obtained after times. In the experiments the power required for inserting the circuit ends into the multiconnector was about 10.5 kg. and that for pulling it out from the multiconnector was approximately 8.5 kg. It appears from this graph that the resistance value of each female terminal of the present invention multiconnector hardly varies, even after the circuit ends of the printed-circuit board are inserted into and pulled out from the multiconnector many times.

FIGURES 16A and 16B illustrate other characteristics of the multiconnector of this invention, obtained with the same female terminals and circuit ends as those used in the experiments of FIGURES 14 and 15. FIGURE 16A shows the resistance values of the female terminals of the multiconnector holding the printed-circuit board therebetween when subjected to vertical vibration. FIG- URE 16B similarly shows the resistance values of the female terminals when subjected to horizontal vibration. In each graph the ordinate and the abscissa represents the same as those in FIGURES l4 and 15. The amplitude of the aforementioned horizontal and vertical vibration was 1.5 mm. and the time of its application was minutes and its period was 60 seconds. As will be seen from the graphs, the resistance value of each female terminal hardly varies. In FIGURE 16A the curve C represents the resistance values of the female terminals after the vibration test and the curve C those before the test.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

What I claim is:

1. A multiconnector comprising an insulating base having a groove for a circuit end to be inserted therein and a gap contiguous to the groove, and a female terminal making contact with the circuit end inserted into the groove, the female terminal consisting of a first resilient contact strip and a second resilient contact strip cooperating therewith, the first resilient contact strip having a base portion to be passed through the gap and a contact curved portion contiguous to the base portion which has formed therein a longitudinal slit, the second resilient contact strip having a base portion to be passed through the gap and a curved contact portion contiguous to the base portion which has a pair of engaging projections formed at the free end thereof and projects from the wall of the groove to the center of the groove through the slit, the width of said engaging projections selected to be greater than that of the slit, the curvature of the curved contact portion of the first resilient contact strip being greater than that of the curved portion of the second resilient contact strip, the first and second resilient contact strip being arranged in such a manner that the curved contact portion of the first resilient contact strip is disposed at the insertion side of the circuit end,

2. A multiconnector as claimed in claim 1, wherein the first resilient contact strip has two projecting contact portions and the second resilient contact strip has a projecting contact portion, the projecting contact portion of the second resilient contact strip being disposed between the two projecting contact portions of the first resilient contact strip, all the projecting contact portions of the first and second resilient contact strips being arranged substantially on the same plane which intersects the base portions of the first and second resilient contact strips at an acute angle.

3. A multiconnector as claimed in claim 1, wherein the first resilient contact strip has two projecting contact portions and the second resilient contact strip has a projecting contact portion, the projecting contact portion of the second resilient contact strip being disposed between the two projecting contact portions of the first resilient contact strip, all the projecting contact portions of the first and second resilient contact strips being arranged substantially on the same plane which intersects the extension of the inner wall of the groove above the groove at an acute angle.

4. A multiconnector as claimed in claim 1, wherein the first resilient contact strip has two projecting contact portions and the second resilient contact strip has a projecting contact portion, the projecting contact portion of the second resilient contact strip being disposed between the two projecting contact portions of the first resilient contact strip, all the projecting contact portions of the first and second resilient contact strips being arranged substantially on the same plane which is substantially parallel to the inner wall of the groove.

5. A multiconnector as claimed in claim 1, wherein the first resilient contact strip has a lug projected from the base portion in the vicinity of the portion contiguous to the curved contact portion and a tongue set up from the base portion spaced a predetermined distance from the lug so as to attach the female terminal to the insulating base.

References Cited UNITED STATES PATENTS 3,131,017 4/ 1964 Mittler.

2,071,713 2/ 1937 Terrill 339-260 2,781,498 2/1957 Maly 339-258 3,040,291 6/ 1962 Schweitzer et al. 3,172,718 3/1965 Lalonde 339-217 3,274,532 9/ 1966 Engel.

FOREIGN PATENTS 611,497 10/ 1948 Great Britain.

48,994 6/1966 Germany.

MARV-IN A. CHAMPION, Primary Examiner. R. STROB-EL, Assistant Examiner. 

